1. Field of Invention
The present invention relates to a method for making a poly-lactic acid/silica composite and, more particularly, to a method for providing a poly-lactic acid/silica composite with excellent mechanical properties without affecting the biodegradability.
2. Related Prior Art
As the time advances, various plastics, composites and polymers have been developed. However, the development of the polymers entails a huge amount of materials that cannot be biodegraded in the environment. This huge amount of un-biodegradable polymers imposes a grave threat for the environment and therefore our life. In 1980s, the global demand for plastics reached 200 million tons. It consumes a lot of resources to incinerate or burry plastic waste since most of it is un-biodegradable. Moreover, the incineration of plastic waste results in the emission of the greenhouse gas that causes the global warming.
Conventional plastics such as polyester (“PET”), nylon, acrylics and polypropylene (“PP”) exhibit excellent physical properties; however, they pollute the environment since they cannot be degraded fast. Poly-lactic acid (“PLA”) is a biodegradable polymer that can be used without imposing a grave problem to the environment; however it exhibits dissatisfactory physical properties. The glass transition temperature of poly-lactic acid is about 60° C., and the melting point of poly-lactic acid is about 170° C. Obviously, the thermal properties of poly-lactic acid are inadequate to encourage replacement of the conventional polymers with poly-lactic acid.
Inorganic materials may be added to polymers to enhance the physical and thermal properties of the polymers. Conventionally, inorganic silica is mixed with polymers without providing chemical bonds between the silica and the polymers.
The present invention is therefore intended to obviate or at least alleviate the problems encountered in prior art.